I saw young and old pple slotting lots of coins and trying to
grab those psp nitendo dls, etc....knowing that it is a
gimmick.
And recenly saw a new games, shooting fishes down...so many
adults are playing the games.
Were it get addicted?
Why spend money to play this games?
Why waste time and energy?
1) Yes, it is possible to get addicted. MMORPG, arcade games,
...etc. all these games can get one hooked on them.
2) Because they are not free and most cannot be downloaded
online? Shooting games are also not as fun without a "gun" to
hold.
3) It was on newspaper, the game machine which you talked about.
A lot of those interviewed said that they have nothing to do at
home, and have the cash to spare anyway. Personally, I find it a
bit like toto and 4D, the chances of striking are low, but people
play them anyway.
For the fishing games, it actually does make one feel rich if
you are good at it. 
There are actually quite a number of people
whom I saw who are able to start with a handful of coins and end up
with a basket or two of coins. I am not sure if you can actually do
anything else with the coins though.